# Phyiscs - Recall for Chapter 5: Work, Energy and Power

> Source: https://ollybritton.com/notes/a-level/physics/recall-questions/chapter-5-work-energy-and-power/ · Updated: 2021-08-03 · Tags: physics, school, work-energy-and-power, recall-questions

## Recall Questions
##### Define work done (enerhgy transferred by a force)??
Work done = Force x distance moved in __direction of force__

##### How much work is done on an object by a force acting at right angles to the direction of motion of an object??
None.

##### Define power??
Rate of work done/Rate of energy transfer

##### Define the Watt??
$$1W = 1Js^{-1}$$

##### Define the Joule??
Work done to move a force of $1N$ (through) a distance of $1m$ through the point of application.

##### State the principle of the conservation of energy??
Energy cannot be created or destroyed; it can only be transferred/transformed.

##### Why are energy transfers in the real world not 100%??
The efficiency of a device is always less than 100% because of heat losses due to friction/air resistance.

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